System and method for providing a graft in a vascular environment

ABSTRACT

An apparatus is provided that includes a graft for coupling two vascular conduits within a patient. The graft includes: 1) an anchor system that forms an arc at one end of the conduits; and 2) a body element coupled to the anchor system. The anchor system comprises a biodegradable stent. In particular embodiments, portions of the graft are either self-expandable or balloon-expandable. In still other embodiments, anchor system includes NITINOL and the anchor system is substantially self-sealing at one end of the conduits. In one embodiment, the body element comprises polytetrafluoroethylene (PTFE) or expanded polytetrafluoroethylene (EPTFE). In yet other embodiments, the body element includes either a gelatinous or an elastomeric coating disposed on its surface.

RELATED APPLICATIONS

This Application is a divisional (and claims the benefit of priorityunder 35 U.S.C. §120 and §121) of U.S. application Ser. No. 11/483,121,filed Jul. 7, 2006, now U.S. Pat. No. 7,722,665 entitled “SYSTEM ANDMETHOD FOR PROVIDING A GRAFT IN A VASCULAR ENVIRONMENT,” Inventor(s)Azam Anwar, et al. The disclosure of the prior application is consideredpart of (and is incorporated by reference in) the disclosure of thisapplication.

TECHNICAL FIELD OF THE INVENTION

This invention relates in general to vascular procedures and, moreparticularly, to a process, a system, and a method for providing a graftin a vascular environment.

BACKGROUND OF THE INVENTION

The treatment of vascular diseases has grown exponentially in terms ofsophistication and diversity. Procedures involving items such as stentsor balloons are virtually routine in many health-care practices.However, despite vast advancements in many vascular procedures andmedical devices, one particularly troublesome issue has remained in thefield of kidney dialysis.

The number of patients requiring hemodialysis treatment grows at analarming rate. Because patients generally require treatment until deathor until kidney transplantation, the projection for the number of futurehemodialysis procedures increases with each new group of patients.

Augmenting this problem is the prevalence of diabetes, which contributesdirectly to the number of patients requiring some form of kidneydialysis treatment. Currently, statistical data indicates thatapproximately twenty (20) million Americans have chronic kidney disease(CKD), while another twenty (20) million are at risk. Projections forthe current population of patients with end-stage renal disease (ESRD)(which represents CKD patients requiring dialysis) are disturbing:reaching nearly 325,000 in 2002 with more than 100,000 patientsbeginning dialysis in 2003. Conservative estimates indicate that theprevalent rate of patients with ESRD is growing at approximately 3% peryear and this rate is significantly higher in older populations (e.g.the 45-64 year range).

Concisely stated, current dialysis grafts are simply not ideal for amultitude of reasons. Many of the current shortcomings are describedbelow in greater detail. These grafts can cause setbacks to the patientdue to poor instrument design, adverse reactions from the patient'sbody, and higher costs for all individuals involved.

Accordingly, the ability to properly address vascular issues involvingconduits within a suffering patient presents a significant challenge fordevice manufacturers, physicians, and surgeons alike.

SUMMARY OF THE INVENTION

From the foregoing, it may be appreciated by those skilled in the artthat a need has arisen for an improved process for achieving superiorflow, minimal stenosis, and optimal patency in a given vascularenvironment. In accordance with an embodiment of the present invention,a device, a system, and a method for facilitating optimal connectionsare provided that substantially eliminate or greatly reducedisadvantages and problems associated with conventional vasculardevices, approaches, and strategies.

According to an embodiment of the present invention, an apparatus isprovided that includes a graft for coupling two vascular conduits withina patient. The graft includes: 1) an anchor system that forms an arc atone end of the conduits; and 2) a body element coupled to the anchorsystem. The anchor system comprises a stent, which may be biodegradable,bioabsorbable, or biostable. In particular embodiments, portions of thegraft are either self-expandable or balloon-expandable. In still otherembodiments, the anchor system includes NITINOL and the anchor system issubstantially self-sealing at one end of the conduits. The body elementcomprises polytetrafluoroethylene (PTFE), expandedpolytetrafluoroethylene (EPTFE), polyurethane derivatives, or any othersuitable materials. In yet other embodiments, the body element includeseither a gelatinous or an elastomeric coating disposed on its surface.

In still yet other embodiments, the body element includes two materials,whereby one of the materials biodegrades at a rate that is differentfrom the other material. Additionally, both the body and the anchor mayinclude a coating or a wrap to be used for drug loading and drugalluding.

In more specific embodiments, the graft may be accompanied by a deliverysystem that is used to direct the graft to a target location, thedelivery system including a perforated sheath, a plunger, and a basethat is coupled to the plunger, whereby actuation of the plunger candirect the graft to its target location. There are a myriad of possibledesign choices for the present invention, many of which are detailedbelow. The audience should be aware that the present invention isreplete with potential design elections/alternatives or deviations fromthe specifications or examples provided herein in this document.Accordingly, the present invention and its appended claims should beconstrued to encompass all such modifications.

Certain embodiments of the present invention may provide a number oftechnical advantages. For example, according to one embodiment of thepresent invention, an architecture and a process are provided that offera flexible AV graft system for a surgeon to utilize. The graft includesa hemodynamic profile, which reduces scarring or occlusion-typecomplications that would otherwise arise. In addition, the graft of thepresent invention offers a unique anchoring system that is stable andthat is not prone to subsequent intimal hyperplasia. Many existing graftsystems produce unwelcome radial forces, which present a significantdanger to the patient. The present invention overcomes thesedeficiencies (as well as others) because the anchor of the graft can besecured within the vessel (vein or artery): yielding minimal radialforces. Radial forces must be accounted for because they can serve toinjure vessels. In an ideal scenario, the graft is self-sealing;although various types of sutures can be used if this is not the case.In one example embodiment, an abrasive material can be used to createenough frictional force that the anchor is stabilized.

Moreover, the graft structure of the present invention is advantageousbecause it can be leveraged to deliver drugs locally: either through astent, an anchoring system, the body of the graft, a coating, a wrap, orany other suitable element. Due to many of the aforementioned beneficialcharacteristics, the architecture of the present invention can provide anew graft solution with significantly higher long-term patency rates.

Certain embodiments of the present invention may enjoy some, all, ornone of these advantages. Other technical advantages may be readilyapparent to one skilled in the art from the following figures,description, and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

To provide a more complete understanding of the present invention andfeatures and advantages thereof, reference is made to the followingdescription, taken in conjunction with the accompanying figures, whereinlike reference numerals represent like parts, in which:

FIG. 1A is a simplified schematic diagram illustrating a vein and anartery, which may subjected to an example vascular procedure using agraft in accordance with one embodiment of the present invention;

FIG. 1B is a simplified schematic diagram of the graft in which the bodyof the device is reinforced;

FIG. 1C is a simplified schematic diagram of an alternative embodimentof the graft in which each side of the device is suitably secured to thevein and the artery;

FIGS. 1D-1G are simplified schematic diagrams illustrating an exampledeployment of the graft;

FIGS. 1H-1I are simplified schematic diagrams of the graft beingimplemented in one example scenario;

FIGS. 1J-1L are simplified schematic diagrams illustrating severalexample implementations of an anchor of the present invention;

FIG. 2A is a simplified schematic diagram of a patient's arm after theconnections have been formed;

FIG. 2B is a chart that depicts disadvantages and advantages ofpotential conduits utilized in arteriovenous access situations;

FIGS. 3A-3B are simplified schematic diagrams that illustrate an exampleof a patient's arm before and after a procedure involving the presentinvention has been performed;

FIG. 4 is a simplified schematic diagram illustrating severalconnections that were created in a patient's arm using the graft of thepresent invention; and

FIGS. 5-12D are simplified schematic diagrams illustrating one set ofdimensions and/or design possibilities for the graft and delivery systemof the present invention.

DETAILED DESCRIPTION OF THE INVENTION

For purposes of teaching and discussion, it is useful to provide someoverview as to the way in which the following invention operates. Thefollowing foundational information may be viewed as a basis from whichthe present invention may be properly explained. Such information isoffered earnestly for purposes of explanation only and, accordingly,should not be construed in any way to limit the broad scope of thepresent invention, its potential applications, and the appended claims.

For patients with end stage renal disease (ESRD), dialysis helps toremove waste, to balance certain chemicals in the blood, to removeexcess fluid, and to control blood pressure. The survival of patientswith ESRD is dependent on dialysis. There are two modalities ofdialysis: hemodialysis and peritoneal dialysis, the former being themost common modality. In order to perform a hemodialysis procedure, alarge vascular access is required. There are several methods of accessavailable, several of which are outlined below.

Hemodialysis catheters are used in virtually all new patients, whilethey await the maturation of their permanent treatment method using anarteriovenous (AV) fistula or AV graft. A fistula is a tube-like passagethat extends from a normal cavity or tube to a free surface or toanother cavity. Fistulas are generally desirable as a long-termtreatment method. However, there are drawbacks with fistulas because: 1)there is a limited number of vessels in many patients; 2) there is ahigh likelihood of failure in diabetics; 3) there are few favorableveins in diabetics (i.e. veins having sufficient width and elasticity);and 4) the problem of intimal hyperplasia at the venous anastomosis isstill present.

Current AV grafts are used primarily when AV fistulas are notrecommended due to age considerations or diabetic conditions. However,the development of a new type of AV graft with higher patency ratescould make grafts the preferred method of access for hemodialysis.Another advantage of grafts is that grafts can be used almostimmediately (such that puncturing of the graft is readily permitted),whereas fistulas need considerably more time.

Because most of the growth in hemodialysis patients is due to diabetesor due to patient age (ranging from 45 to 64 years old), the current AVfistula method is often not a viable option. Therefore, a growing numberof patients require AV grafts. However, current graft solutions areproblematic, as they have unacceptably low long-term patency rates.

The present invention overcomes these problems (and others) in providingan ideal graft that addresses the issues presented above. The proposedsolution of the present invention introduces a new type of AV graft. Themain benefits of the new graft are a hemodynamic profile, a uniqueanchoring system, an ability to deliver drugs, and an improvedconstruction, which can accommodate the use of a biodegradable material.The architecture of the present invention also offers a new AV graftsolution with significantly higher long-term patency rates and which ismuch safer for the patient.

Note that the most common cause of graft failure is stenosis of theoutflow vein, resulting in graft thrombosis. Modalities to treat failedgrafts include: 1) surgery; 2) angioplasty with balloons and/or stents;and 3) declotting using devices or drugs. The surgical revision using ajump graft may extend the access further up the arm to a more centrallocation. However, after angioplasty, the access is immediatelyavailable for use and the available veins are saved for future use.Also, angioplasty is an easy and safe procedure, representing a superiorsolution, which is in contrast to repeated surgical revisions. A recentstudy has shown a 77% reduction in the intimal hyperplasia at the venousanastomosis using sirolimus-eluting stents, as compared to bare metalstents. The graft patency after an initial intervention is approximately40%. As expected, longer stenoses and those lesions that have beendilated several times have less favorable patency rates.

In regards to the treatment of a clotted graft, the pulse-spraypharmacomechanical thrombolysis (PSPMT) helps to salvage around 75-94%of grafts. Statistical evidence suggests that the primary patenciesrange from 24% to 34% at 6-months and the secondary patencies may reach80%. Thrombectomy devices have increased the efficiency and speed ofthrombus removal and, in certain cases, obviate the use ofthrombolytics. After a thrombectomy, the venous outflow stenosis shouldbe treated. Thrombectomy of an infected graft is an absolutecontra-indication since revascularization may lead to fatal sepsis.However, signs of infections can be very subtle and an infection can bemissed. Other complications of thrombectomy include: anemia, bleeding,acute cardiac events, and venous and arterial embolism.

The proposed “Ideal Graft” of the present invention is a device thatoffers an optimal flow profile (producing minimal turbulence), that actsas a backbone for endothelial progenitor cells seeding (EPCs seeding),and that anchors to the vein through a system that can deliveranti-proliferate, anti-thrombotic, anti-platelet, and anti-inflammatoryagents to the surrounding tissues. The graft's body and/or anchor can bebiodegradable and the system, in certain embodiments, is sutureless, asoutlined in greater detail below. The inside of the graft's body and/oranchor can be coated with anti-coagulants, anti-platelets, orthrombolytics. The present invention has advantages over existingsystems because of its placement into a vessel, the two-component system(anchor and body), and all the potential design configurations thatcould be accommodated by such a device. In addition, the presentinvention can readily be used in artery-vein connections, vein-veinconnections, and artery-artery connections (e.g. potentially involvingthe lower extremities). Many of the potential design choices are furtherdetailed below with reference to the FIGURES.

Turning back to FIG. 1A, in one embodiment, device 10 is a graft thatincludes two parts: anchor 12 and body 14. These pieces are integral or,in other embodiments, can be separated or connected in any othersuitable manner. The graft can be made of expandedpolytetrafluoroethylene (ePTFE) or PTFE: both of which represent abio-stable substance that can be optimal in many vascular applications.More specifically, ePTFE is a hydrophobic material that offers superiorwaterproof performance.

Because repeat puncturing presents a significant bleeding issue for thepatient [i.e. there is a sealing problem], the ePTFE can be coated withan elastomeric, gelatinous, or membrane that better accommodatesimproved sealing and a subsequent repuncture. ePTFE could be puncturedimmediately after being placed. In addition, ePTFE is beneficial becauseit is porous (which further allows tissue to grow directly on thedevice) and because it can be sewn into the vein. Tissue growth wouldessentially close the pores of the ePTFE.

Note that two preeminent considerations in constructing the graft areflow dynamics and the optimal delivery of drugs. For the patient,scarring would commence immediately after the procedure was performedand, hence, the drug aspect of the device is crucial. Venous stenosiswill present a significant issue for both the patient and the physician;however the acuteness of this issue will be lessened considerably byoptimal drug applications. The graft itself will stabilize within-growth, shortly after placement.

The use of sutures will assist in this stabilization. Such sutures maybe of a conventional type, purse string, interrupted sutures, or theymay use a screw-type configuration in which pressure applied to the headof the suture translates into a rotational force that secures/tightensan intermediate object in place. In an ideal scenario, the graft securesitself (i.e. self-sealing) after the dilator and the splittable sheathare removed from the target site, whereby little of the graft anchor(e.g. NITINOL or any other suitable composite) is left exposed. However,in cases where stabilization is tenuous, then suturing (either at points18, or 20 on the venous side where the anchor system is present) wouldbe performed.

FIG. 1B is a simplified schematic diagram of the graft in which body 14of device 10 is reinforced with internal scaffolding. FIG. 1B alsoillustrates the use of footers 22, which can assist in securing thegraft in place. FIG. 1C is a simplified schematic diagram of analternative embodiment of the graft in which each side of device 10 issuitably secured to the venous and arterial sides of the connectionusing footers 22 and 24. In still other scenarios, circumferentialhooks, legs, or tines can be used to better fixate the device.

In order to avoid kinking, spatulation techniques may be employed. Inaddition, an abrasive material (either a coating or the underlyingstructure itself) may be used to seat the device. This material couldprovide a frictional resistive force that would inhibit movement on theanchor side where stabilization is more tenuous.

FIGS. 1D-1G are simplified schematic diagrams illustrating an exampledeployment of the graft. FIGS. 1H-1I are simplified schematic diagramsof the graft being implemented in one example scenario. Essentially, thedevice can be composed of two components: 1) the body of the graft(where the dialysis machine will be hooked and where dialysis takesplace); and 2) the anchor, which will anchor the graft inside the vein.The body of the graft can include a stent graft, whereby the cells arelarge enough to enable the dialysis staff member to puncture the graftwith a needle. Alternatively, the graft can be made of a regular graft(without a stent), which is attached to the anchor.

As evidenced by FIGS. 1H-1I, the graft can be anchored within the veinand not necessarily to the vein. This is important for reducing a numberof potential patient complications. The opening where the graft wouldenter the vein is approximately 3 millimeters, but this parameter couldchange considerably due to specific patient/vein characteristics.Additional details relating to other example procedures andconfigurations are provided below.

In one embodiment, the graft is constructed of a self-expandable NITINOLanchor, which can readily be compressed before the device is placed. Inother embodiments, the NITINOL could be replaced by any other suitablymetal or alloy. In certain instances, NITINOL may be prone to fracturingand thus, other metals may be used without departing from the spirit andscope of the present invention. Virtually any material that givesstructural integrity to the graft can be used. The expansion property ofthe anchor would allow the venous side to expand over time. The radialstrength can be selected based on matching potential compliance with thevein or specific vein characterizes. For placement of the graft, theNITINOL anchor portion would be suitably compressed and then insertionof the device would occur on the venous side.

In particular embodiments, the proposed graft anchor is constructed of abiodegradable material that can dissolve (to varying degrees) in thebody of the patient. Note that the cover or shell of the graft could bebiodegradable, whereby an underlying latticework structure is used thatis not biodegradable. This represents the use of at least two materials.In such a case, the underlying structure could be spiral or cylindrical,such as that depicted by FIGS. 1B-1C, or the underlying structure may beof any other requisite shape. One configuration could be underlyingstructure, drug, dissolvable barrier, or any other suitable combinationthereof. The outer layer could be any suitable material such as thosematerials disclosed in U.S. Pat. No. 7,033,603, entitled: Drug ReleasingBiodegradable Fiber for Delivery of Therapeutics; U.S. Pat. No.6,858,222, entitled: Fabrication of Drug Loaded Biodegradable PolymerFibers; and U.S. Pat. No. 6,596,296, entitled: Drug ReleasingBiodegradable Fiber Implant. Some other possible configurations arefurther explained below.

In certain instances, the entire graft could be biodegradable. Hence,the graft could be partially biodegradable or fully biodegradable. Itshould also be recognized that two different biodegradable materialscould be used in combination such that one material could dissolve moreslowly than the other material. The slower dissolving material couldfunction as a backbone or a skeleton for the graft: providing supportfor the device as it acclimates to its new environment. Any suchpermutations are clearly with the broad scope of the present invention.

In one embodiment, anchor 12 comprises a biodegradable material suchthat, over time, anchor 12 would dissolve at a selected pace. Any drugagent could be used to facilitate a dissolution objective of anchor 12.A coating or a wrap (e.g. a polymer, a fibrous material, etc.) could beused to assist in the drug deliver and/or assist in connecting orsupporting anchor 12. Thus, in one example scenario, a simple polymercould be used on the surface of anchor 12 to inhibit fibrointimalhyperplasia (i.e. excessive growth of tissue).

Body 14 could comprise ePTFE, a polyurethane derivative, an elastomericcomposite, or a gelatinous material. In one example, body 14 is notnecessarily biodegradable such that it maintains its structuralintegrity. Other embodiments however allow body 14 to biodegrade (tovarying degrees).

In terms of placement of the graft and its potential design [in theartery and vein combination embodiment], body 14 could be in the rangeof 3-9 millimeters in one example. Anchor 12 could extend 1-60centimeters into a vessel (artery or vein) once it has been positioned.In general, there is little downside risk to having the anchor extendfurther into the vessel, as opposed to less. The longer the anchor, themore stable the device. Some obvious drug applications for the anchorwould include heparin or any other suitable anticoagulant oranti-platelet.

The arc created by anchor 12 could be of any suitable degree measurement(e.g. 45 degrees), but in any event, should universally be gradual orsmooth. The smoothness of the arc will facilitate a preferredhemodynamic profile. If the angle is too acute, the system will clotoff, which is undesirable. A 90-degree angle, for example, would not beideal and may cause the graft to kink or cause blood turbulence. Theactual thickness or diameter of anchor 12 and/or body 14 could be in therange of 3-6 millimeters, while the small lip formed by the vein on oneend of body 14 could be approximately 1.5 millimeters. Note that all ofthese specifications are only being provided by way of example. Thesemeasurements may be departed from considerably while still achieving theteachings of the present invention.

One important issue in procedures involving the graft of the presentinvention involves exposing the vein to various drugs, which can assistin the healing process and/or inhibit complications that normally occurin dialysis scenarios. In general, the venous side is more problematicand, hence, higher dosages of drugs should be delivered there. Such drugapplications could have dosages that release over long periods of time;ideally, the longer the drug delivery, the better. It should also benoted that the selection of veins is critical. Veins less than 2millimeters would probably not be feasible for such a graft procedure.Vein selection could be aided by sonography or other adequatetechnologies. It should also be noted that a Seldinger approach may bepreferred to a simple veinotomy.

FIGS. 1J-1L are simplified schematic diagrams illustrating exampleimplementations of anchor 12. In FIG. 1J, there are a number of struts52 of an associated stent. An exterior cover 50 is biodegradable,bioabsorbable, or biostable. Note that any of the materials in thesecomponents could include drugs disposed directly thereon, or inherentwithin, such that the drug releases over time. This exterior materialcould include materials such as polyurethane, ePTFE, or a simpleplastic/rubber derivative.

FIG. 1K illustrates the scenario in which two materials envelop thestent in a sandwich configuration. FIG. 1L illustrates an example inwhich a polymer 58 surrounds a stent (or any other suitable structure).The polymer can carry the drug and/or dissolve over a certain timeperiod. It should be evident to the audience at this juncture in theSpecification that the present invention is replete with potentialdesign choices. The use of polymers, drugs, coatings, wraps,polyurethane derivatives, gelatinous, and elastomeric materials, stents,tubes, ePTFE, PTFE, and Dacron, etc. each represent a design choice thatmay be applicable for a given environment or scenario. The presentinvention encompasses any and all combinations of these elements. Forpurposes of brevity, the inventors have only provided an example set ofdevices for purposes of teaching and discussion.

FIG. 2A is a simplified schematic diagram of a patient's arm after theconnections have been formed by the attending surgeon. Note that thedissolution of the graft will cause new endothelial cells to replace thestructure of the graft. The endothelium is the layer of thin flat cellsthat lines the interior surface of blood vessels, forming an interfacebetween circulating blood in the lumen and the rest of the vessel wall.Endothelial cells line the entire circulatory system, from the heart tothe smallest capillary. In small blood vessels and capillaries,endothelial cells are often the only cell-type present. Hence,endothelial cells can help to form a new latticework for facilitatingthe blood flow in this area of a patient. Fibrous tissue is the othercomponent in such a paradigm: together the fibrous tissue and theendothelial, cells function to enhance necessary conduit at this site.

FIG. 2B is a chart that depicts disadvantages and advantages ofpotential conduits utilized in arteriovenous access situations.Additionally, there could be any number of combinations of these conduitmaterials, which can be employed by the present invention. For example,the graft can be both constructed of Dacron and ePTFE in an alternativeembodiment. In essence, any number of possible permutations and/oradditional materials could be used for the graft.

FIGS. 3A-3B are simplified schematic diagrams that illustrate an exampleof a patient's arm before and after a procedure involving the presentinvention has been performed. In operation, anchor 12 can be insertedinto a vein and secured within the vein. The anchor system is aself-expandable or balloon-expandable biodegradable drug-eluting stent.The polymer with the active drug can cover the external surface of thestent. In certain embodiments, the anchor system can be used to anchor avein to an artery or, alternatively, to another vein.

One function of anchor 12 is to ensure that the graft is attached to thevein. In still another example deployment, anchor 12 is positioned about2-3 centimeters into the vein. Anchor 12 is designed such that, in itscompressed or delivered state, it is relatively small in comparison tothe point of entry. The material of anchor 12 has a memory such thatwhen a surgeon releases it at the appropriate location, it will occupy amuch larger area. Hence, once anchor 12 has been inserted into the vein,it can be deployed or expanded such that is provides an appropriateresistive force, pressure, or friction, which enables anchor 12 to besomewhat resistant to movement. This feature of anchor 12 minimizesradial forces and hyperplasia issues at this site.

Note that the vein in this example does not have to be necessarilyligated. The positioning of the graft obviates the need to performadditional ligating procedures that address small branches associatedwith this vein. The placement of the graft has the effect of excludingthese branches, rather than having to address each one individually.

Note that vascular access related problems currently account for morethan 25% of all hospitalizations among ESRD patients. Infections,peri-graft seroma, and pseudoaneurysm constitute less than 10-15% ofgraft failure. Instead, the majority is due to graft thrombosis, whichis the result of disproportionate intimal hyperplasia at the venousoutflow tract. The intimal hyperplasia responses occur (predominantly)in the proximal 2-3 cm of the vein just distal to the graft-veinanastomosis. The pathophysiological mechanisms behind the reactiveintimal hyperplasia are believed to be due to increases of flow and tovascular injury. Anchor 12 achieves significant advantages over existinggraft systems in that anchor 12 is secured within the vein and yieldsminimal radial forces. Radial forces must be accounted for because theycan serve to injure vessels or the vein itself.

On the artery side of the graft (where the surgeon is facilitating aconnection between a vein and an artery), body 14 is attached viaanastomosis by suturing. A number of drugs may be disposed on, orwithin, body 14. For example, anti-coagulants, anti-thrombic, or growthfactors may be used in such a scenario. The growth factors may be usedin order to recruit endothelial progenitor cells that expedite recoveryfor a patient. The growth factors may also be used in order to encouragethe formation of new structures (e.g. vessels) at this site.

Hence, the inside (or exterior) of the graft can be coated with, forexample, a CD34 antigen. Additionally, any number of drugs can be usedfor coatings and wraps (e.g. sirolimus, paclitaxel, everolimus, ABT-578,mycophenolic acid, tacrolimus, estradiol, oxygen free radical scavenger,biolimus A9, anti-CD34 antibodies, PDGF receptor blockers, MMP-1receptor blockers, VEGF, G-CSF, HMG-CoA reductase inhibitors,stimulators of iNOS and eNOS, ACE inhibitors, ARBs, doxycycline,thalidomide, etc.).

In operation of an example embodiment, consider the case of a patientwho is experiencing kidney failure. The surgeon in this situation haselected to offer this patient a graft, as outlined herein. There are twoincisions that are made by the surgeon: one at the artery and one at thevein. These incisions effectively localize the vein and the artery. Awire can then be inserted into the vein. The present invention can bepositioned over the wire, whereby the graft is deployed. (Note that thepresent invention may also be deployed in a percutaneous fashion, whichis further detailed below.) Anchor 12 is then suitably positioned withinthe vein. An effective positioning of anchor 12 operates to preventback-slipping or bleeding on the venous side. The wire is subsequentlyremoved from the surgical site. Body 14 can then be sutured to theartery. FIG. 4 is a simplified schematic diagram illustrating acompleted procedure. In this instance, several connections were createdby the surgeon in a patient's arm using the graft of the presentinvention.

In the percutaneous solution, entry can be from the venous or thearterial side. For purposes of discussion, the venous side solution isexplained here. First, the target vein is accessed via a sheath in aconventional manner. Subsequently, a needle (which is specially designedto include a curve) that includes a hole is inserted into the sheath.Note that, for purposes of fluoroscopy, dye may also be injected intothe patient, whereby a simple tourniquet is used to stop the flow ofblood.

With the target under fluoroscopy, the objective is to puncture the wallof the artery where the dye has accumulated. Then a wire can be insertedinto the artery and the sheath can be advanced over the wire anddirected to the artery. Thus, the sheath is now positioned between thevein and the artery. Now the environment is ready for the graft. As isdescribed above, anchor 12 is positioned on the venous side. Inaddition, body 14 is coupled to the arterial side in any suitable manner(e.g. using a resistive force mechanism, using footers or legs that holdbody 14 in place, using a funnel shaped design, etc.).

Turning now to the next set of FIGURES, FIGS. 5-12D are simplifiedschematic diagrams illustrating yet another set of dimensions and/ordesign possibilities of the graft of the present invention. For theseexample FIGURES, and to offer some example dimensions for a potentialgraft design, the approximate diameter of the graft is between 6-8millimeters; the overall length of the of the graft is between 20-40centimeters; the distal graft diameter delivered is <3 millimeters; thedistal anchor graft diameter expanded is between 4-6 millimeters; theapproximate length of the graft anchor into the vein is 2 centimeters;and the potential maximum length of the graft anchor outside the vein is1.5 millimeters.

In addition, the graft material for this example design is ePTFEthroughout the graft's length, where a NITINOL scaffold (about 3.5centimeters) is provided to cover the distal end. A drug-eluting coatingis provided to inhibit intimal hyperplasia. For example, the use ofdrugs such as rapamycin (or other similar drugs) may be used for theirantiproliferative properties. Additionally, in the implementation ofFIG. 5, a drug coating may be placed on both the exterior and theinterior of the body of the graft. A section of ePTFE 60 is provided incombination with a NITINOL stent 62 with a coating.

FIGS. 6A and 6B illustrate a portion of the delivery system componentsfor the graft of the present invention. A simple support-type cathetercould be readily used in such applications. A plunger 70, along with abase 74, and a sheath could also be used in such an architecture. Thedelivery system of FIGS. 6A and 6B is unloaded at this point in time. Amagnified view of a perforated sheath 72 of FIG. 6A is provided by FIG.8. As highlighted above, the delivery of the device can be over thewire. A surgeon should have flexibility in retrieving and delivering thedevice, particularly in percutaneous procedures. Hence, the presentinvention can use any number of peelable components (e.g. peel-awaysheaths) that alleviate some of the burden on the surgeon.

FIGS. 7A and 7B are simplified schematic diagrams that illustrateancillary components of the delivery system of the present invention. Aninner support 80 is provided along with a guidewire lumen 82 inconjunction with a luer fitting with a luer lock 84. FIGS. 10A and 10Bshow the delivery system fully loaded with the graft of the presentinvention, where FIG. 9 provides a magnified view of the tip of FIG.10B. In these FIGURES, the anchor portion of the graft is in acompressed state. FIGS. 11A and 11B illustrate yet another exampleconfiguration before the device is deployed. Again, it should bereiterated that these design choices are not exhaustive and only offerthe audience yet another potential construction of the graft.

FIGS. 12A-D illustrate yet another embodiment of the present invention.In this configuration, the proposed device is a balloon-expandable orself-expanding stent with a bio-degradable cover or a coating of sometype. Hence, instead of appearing as a simple stent design, the deviceincludes an outer layer that gives it a cylindrical shape, as shown inthe FIGURES.

In one sense, this particular embodiment is different from theaforementioned devices (discussed above) in that it is a full anchordesign: capitalizing on the anchor technology discussed heretofore. Inthis complete anchor design, a suitable material (such as thosecoatings, polymers, and layers highlighted above, including thematerials identified in the US patent numbers referenced previously) isdisposed on the surface of the stent. In other instances, the materialis placed within the stent, or any suitable combination being providedexterior to or within the device.

This device can be in the range of 8-200 millimeters, although such aparameter could be changed based on particular needs. This stent couldbe used in a multitude of environments, including: bypass grafts,dialysis grafts, carotid applications, vein grafts, peripheral arteries,as an esophageal and bronchial scaffold to deliver structure and drugsto a targeted area, or in any other vasculature or endovascular setting.

As highlighted in the corresponding FIGURES, the device in thissituation could easily be placed percutaneously. FIG. 12A depicts acoronary artery blockage that is present; the darkened portionshighlight the extent of the occlusion. In such a case, a wire isadvanced over the blockage and then a stent balloon is subsequentlyadvanced, as shown in FIG. 12B. FIG. 12C shows the balloon (or theself-expanding) element at the targeted area. FIG. 12D illustrates thedevice (i.e. the stent with the cover) being suitably positioned suchthat the pathway is now open and the occlusion has been resolved.

It is important to note that the stages and steps in the precedingFIGURES illustrate only some of the possible scenarios that may beexecuted by, or within, the architecture of the present invention. Someof these stages and/or steps may be deleted or removed whereappropriate, or these stages and/or steps may be modified or changedconsiderably without departing from the scope of the present invention.In addition, a number of these operations have been described as beingexecuted concurrently with, or in parallel to, one or more additionaloperations. However, the timing of these operations may be alteredconsiderably. The preceding example flows have been offered for purposesof teaching and discussion. Substantial flexibility is provided by theproffered architecture in that any suitable arrangements, chronologies,configurations, and timing mechanisms may be provided without departingfrom the broad scope of the present invention.

Although the present invention has been described in detail withreference to particular embodiments in FIGS. 1-12D, it should beunderstood that various other changes, substitutions, and alterationsmay be made hereto without departing from the sphere and scope of thepresent invention. For example, although the preceding FIGURES havereferenced a number of components as participating in the numerousoutlined procedures, any suitable equipment or relevant tools may bereadily substituted for such elements and, similarly, benefit from theteachings of the present invention. These may be identified on acase-by-case basis, whereby a certain patient may present a health riskfactor while another (with the same condition) may not. Hence, thepresent device may be designed based on particular needs with specificscenarios envisioned.

Additionally, although the preceding FIGURES have described abody-anchor combination, another possibility of the present inventioncould be two anchors. In such a case, both anchors would seat directlyin the vessel. It should also be noted yet again that the presentinvention is not limited to vein-artery connections, as vein-vein andartery-artery scenarios can certainly be accommodated by the presentinvention.

It is also imperative to note that although the present invention isillustrated as implicating a number of conventional procedures, thepresent invention could be completely percutaneous, as highlightedabove. In essence, the present invention may be applicable to amultitude of environments in which a viable conduit is needed.

Numerous other changes, substitutions, variations, alterations, andmodifications may be ascertained to one skilled in the art and it isintended that the present invention encompass all such changes,substitutions, variations, alterations, and modifications as fallingwithin the spirit and scope of the appended claims. In order to assistthe United States Patent and Trademark Office (USPTO) and additionallyany readers of any patent issued on this application in interpreting theclaims appended hereto, Applicant wishes to note that the Applicant: (a)does not intend any of the appended claims to invoke paragraph six (6)of 35 U.S.C. section 112 as it exists on the date of filing hereofunless the words “means for” are specifically used in the particularclaims; and (b) does not intend by any statement in the specification tolimit his invention in any way that is not otherwise reflected in theappended claims.

What is claimed is:
 1. A method, comprising: compressing a graft forcoupling first and second vascular conduits; positioning one end of thegraft at a first conduit; and positioning an opposite end of the graftat a second conduit, wherein the graft includes: an anchor system havingan expandable end adapted to be coaxially received within the firstconduit such that the expandable end applies a resistive force to thefirst conduit when the expandable end is radially expanded to have agreater inner dimension, the anchor system forming an arc at an openingof the first conduit, wherein the anchor system includes a stent; a bodyelement coupled to the anchor system; and an outer covering surroundingthe anchor system, wherein the outer covering is configured to deliver adrug therapy.
 2. The method of claim 1, wherein portions of the graftare either self-expandable or balloon-expandable.
 3. The method of claim1, wherein the graft is delivered percutaneously.
 4. The method of claim1, wherein a veinotomy or a Seldinger technique is performed inconjunction with placement of the graft.
 5. The method of claim 1,further comprising: loading anti-coagulants, anti-platelets, orthrombolytics on an inside or an outside of the body element.
 6. Themethod of claim 1, further comprising: suturing at least one of theconduits after the graft is positioned.
 7. The method of claim 1,wherein the anchor system is substantially self-sealing at the firstconduit.
 8. The method of claim 1, wherein the body element and theanchor system are integrally formed.
 9. The method of claim 1, whereinthe graft is at least partially biodegradable.
 10. The method of claim1, wherein the graft includes internal scaffolding to providereinforcement to the graft.
 11. The method of claim 1, wherein the stentextends along the body element.
 12. The method of claim 1, furthercomprising: an inner cover opposing the outer cover and defining a spacetherebetween sized to receive the stent, wherein the inner cover isadapted to deliver another drug therapy.
 13. A method, comprising:compressing a graft for coupling first and second vascular conduits;positioning one end of the graft at a first conduit; and positioning anopposite end of the graft at a second conduit, wherein the graftincludes: an anchor system having an expandable stent adapted to becoaxially received within the first conduit such that the stent appliesa resistive force to the first conduit when the stent is radiallyexpanded to have a greater inner dimension, the anchor system forming anarc at an opening of the first conduit; an inner cover surrounding theanchor system, wherein the inner cover opposes an outer cover defining aspace therebetween sized to receive the stent, wherein the inner coveris adapted to deliver a drug therapy and a body element coupled to theanchor system.
 14. The method of claim 13, wherein the anchor system andthe body element are integrally formed.
 15. The method of claim 13,wherein the anchor system is substantially self-sealing at the firstconduit.
 16. The method of claim 13, wherein at least a portion of thegraft is biodegradable.
 17. The method of claim 13, wherein the outercover is adapted to deliver another drug therapy.